John Michell proposed already in 1784 that near compact massive objects gravity would increase so strong that even light cannot escape. At that time Newtonian gravity theory and so called corpuscular (particle) theory of light were dominating, and the idea was that if required escape speed would be exceeding speed of light, then light originating inside or from such distance could escape temporarily but would return. Later, in 1958, David Finkelstein using General Relativity introduced a more strict definition of local black hole event horizon as a boundary beyond which events of any kind cannot affect to any outside observer. This strict definition has lead to information and firewall paradoxes, therefore local event horizon and the notion of black hole is widely re-examined, and several theories has been developed, some with and some without event horizons. Stephen Hawking, one of front line developers of black hole theories, has supposed an apparent horizon to be used instead of event horizon, saying "gravitational collapse produces apparent horizons but no event horizons" and ended up to a conlusion that "The absence of event horizons mean that there are no black holes - in the sense of regimes from which light can't escape to infinity. " This does not mean denying the existence of black holes, it merely expresses the distrust towards the conventional strict definition of event horizon.